Physiotherapy to prevent ventilator-associated pneumonia

People who are admitted to the Intensive Care Unit (ICU) and receive mechanical ventilation are at risk of developing pneumonia. Many factors have been associated with an increased likelihood of developing this "ventilator-associated pneumonia" (VAP), including pre-existing respiratory disease, supine body positioning, and reduced consciousness level.

Clinicians in the ICU would like to prevent their patients from developing VAP, because it increases mortality, length of stay, and healthcare costs. Retention of airway secretions is thought to contribute to the development of the problem.

To combat this, physiotherapists use various respiratory techniques intended to promote the clearance of airway secretion and improve lung expansion. These techniques can include manual techniques applied to the chest wall, delivering larger volume breaths to the patient, and suction of the tube in the patient's airway that connects them to the ventilator.

Previous literature reviews have concluded that respiratory physiotherapy did not cure or improve the rate of recovery from VAP. However, a recent review took a different approach - examining instead whether respiratory physiotherapy techniques could prevent the pneumonia from occuring in the first place.

Five eligible randomised trials (RCTs) were identified, involving over 600 participants. By pooling the data from these trials, some interesting results were generated. Multimodal respiratory physiotherapy significantly reduced the risk of mortality by about 25%, but it was not clear what the mechanism behind this benefit was.

There are at least 2 ways that respiratory physiotherapy might reduce mortality. The first is by preventing the pneumonia developing. Although the trend here was favorable, it did not reach statistical significance. The second way that respiratory physiotherapy might reduce mortality is by hastening the patient's recovery (because the longer time you remain critically ill and on a ventilator, the higher your risk of death is). The effect on length of stay in the ICU was favorable but again it did not reach statistical significance.

One possibility that the authors appropriately considered was whether the finding on mortality was just a chance finding. However, as an outcome measure, death is not affected by vagaries of diagnostic criteria or biases of unblinded investigators, so with data on 535 participants it is hard to argue that this was not a real finding.

Overall, the most likely explanation seems to be that the effect on mortality is real, and while it may have occurred via a reduction in VAP and/ or length of ICU stay, we cannot be certain about the intervention’s effects on those outcomes.

Importantly, there was substantial imprecision in the review's estimates of the effects on pneumonia and length of stay. This is important because the imprecise estimates do not exclude the possibility of very worthwhile effects on VAP incidence and length of ICU stay; therefore, these outcomes should be the focus of further investigation in rigorous trials.

Want to read deeper into this topic? Have a look at the free full text version of this article published in Journal of Physiotherapy!

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